class SolarSystem(object):
    def __init__ (self):
        # set of names
        self.planet_names = []
        # dict of names -> masses
        self.masses = {}
        # dict of names -> np array * 3
        self.positions = {}
        # dict of names -> np array * 3
        self.velocities = {}
        # dict of names -> np array * 3
        self.acceleration = {}
        self.simulated_time = 0.0
        self.kinetic_energy = 0.0
        self.potential_energy = 0.0

    def __str__(self):
        return str(self.__dict__)

    def __repr__(self):
        return str(self.__dict__)
        
